DIY Calibrators Please Read - Grayscale is NOT Color Decoding (1 Viewer)

[Robert P. Jones]

Maybe off the top of the list, Guy, but never to the nether world.

Your posts are always topnotch, and required reading in this community.

Mr Bob

 

[Fernand]

I want to take this moment to thank Guy for taking a great deal of time to enlight us in this difficult (for me) procedure of calibration.

I'm going to adjust the grayscale patterns by unplugging the Chroma cables (Pr, Pb) and leaving only luma (Y). In terms of red push calibration, I'm gonna use the AXPL and AXNT settings (I have a WEGA).

Am I on the right track???

 

[James Zos]

Fernand, this thread has been here for a long time, with no new posts. You might get a better response if you posted your question as an entirely new thread.

 

[Fernand]

You're right on the money! I'll do that. Thankx!

 

[Robert P. Jones]

Fernand -

You are on the right track for the greyscale, about getting perfect B/W by undoing the Pb and Pr, leaving the Y as the only connection. Y is perfect, empirical B/W.

This procecdure can also be used to do the greyscale on component HD if you don't have a HD generator, and it can make the AVIA greyscale patterns perfect to use also, since they are flawed on the greyscale patterns.

Without disco'ing the Pb and Pr, the AVIA greyscale patterns are not dead on the money B/W - tho VE's are - and on a Tosh you don't want to be changing the Color intensity level at all from where you wil be having it set during viewing, when calibrating the greyscale there, in an attempt to get true B/W. If you turn Color all the way down in an attempt to get B/W, you get kryptonite green on many Tosh RPTV models. I don't know about their DVs.

I also don't know about the Wegas, on those particular registers. Hopefully you have taught me something new here.

Mr Bob

 

[Fernand]

By trial and erroring I now know the essential settings in the WEGA service menu for calibration. If you need something let me know.

 

[Robert P. Jones]

Yes, please! I will print them out and carry them with me on cals, and definitely store them in reference files.

I tried experimenting with a Sony 34" HD 1 once, and several of the experimentations resulted in instant shutdown of the unit, with a spiral trail of the beam in the middle of the screen before it went black.

You don't think my heart did flipflops on that one, every time I decided that yes, it was PROBABLY OK to turn the set back on again now...

I was lucky, and none of those adrenalin-producing clicks from zero to one or vice versa caused any damage to the unit. But I have seen trails like that leave permanent, indelible marks on the phosphors of the much smaller and more concentrated - and much harder driven - liquid cooled RPTV CRTs.

Trust me - on this kind of thing, I would definitely rather benefit from somebody else's trial and error, than my own!

Mr Bob

 

[Andrew W]

Hi Bob,

Do you mind if I ask a few questions about grayscale on my KP57XBR10W? I bought a Spyder with OptiCAL and followed the proc on the HS10 Yahoo group to adjust my set to D65 at 20IRE and 80IRE. After that, I recal'd the color using Avia. The picture is greatly improved just stopping at this point, best ever in two years since we bought it.

But the x/y and temp don't track completely straight through the 40, 50, 60IRE screens (high as 7700.) I only adjusted DRV and CUT items. Are there other items to make the tracking more linear? Should I play with slightly defocusing blue gun?

Thanks,

Andy

PS: I'm sure you would do a much better job than me, but I can't afford to fly you here right now.

 

[Robert P. Jones]

Grayscale is like a 6 piece hanging mobile - you pull on one of the 6, and all of the other 5 are also affected.

The 3 cuts and 2 or 3 drives are all there is for grayscale.

Very few RPTVs track grayscale with complete accuracy. One of the talents that has to be devoloped when you are a calibrator is knowing what the compromises are and where you have to make them, for best optimization of your picture.

The blue defocussing inversely mimics the blue drive, and will not make your grayscale track any more accurately. The bottomline accuracy of your grayscale tracking is determined by the quality of the instrument you are aligning.

Mr Bob

 

[John Morton]

Wow is this a great thread. Thanks to everybody!!

 

[Jim Wilke]

Any plans to come to Anchorage, Alaska?

 

[Robert P. Jones]

Send me a plane ticket and then ask me that.

Mr Bob

 

[Vader]

Hi all,

I just sat down to calibrate my Mitsu 65511, and found that when calibrating the tint/color, while I can get blue to line up just fine, the red and green are off. My understanding is that this is a common problem with color decoding in NTSC (less so for PAL). If I understand the posts up to now correctly, this is not a grayscale problem, but one of color decoding. Further, can I assume that by adjusting the colors red and green independently in the service menu, this would not affect the blue (which is dead-on), or the grayscale settings themselves? I have no idea how to invoke the service menu for the Mitsu, or even if I should (I am by no means a professional). Even then, the only way I would touch these settings is if there were three bars to adjust the three primary colors (like the contrast, brightness, etc in the user menu), and there was a "reset to default" option. I would appriciate any suggestions anyone can give. Thanx!

Vader

"Impressive. Most impressive."

 

[ChrisWiggles]

"Further, can I assume that by adjusting the colors red and green independently in the service menu, this would not affect the blue (which is dead-on), or the grayscale settings themselves?"

No, adjusting red/green/blue gun gains is a global adjustment and would affect grayscale. read the linked thread that explains this more in-depth.

 

[Robert P. Jones]

Actually the Mits grayscale registers are global only on User Low, and on User High are local to the scanrate involved when in Service Mode. You will find the grayscale registers for Low with an L at the end, and for High with an H at the end, in SM.

Mit has had red push designed into their colorations paradigm since long before ANYB0DY's HDreadys came about. In the older versions it was defeatable on certain model year, in the User Color Bias section, under the heading of "Accurate". As opposed to Skin-tone and Average, both of which were red pushed. If I had had Guy's AVIA at that time, I woulda known that about my VS-6017, which had those User settings available.

Whenever there is red push - or any other kind, today I cal'd a Sony LCD 50" HDready and had to deal with red diminish! - you cannot trust the blue isolation/filter test. You will get blue perfect, and the red will still stick out like a sore thumb on a redpushed system.

The only way to do it without realignment of the color decoder or addition of an attenuator if you have your info going in on component inputs, is to do it very carefully by eye and hope for the best.

Mr Bob

PS - I have always used both AVIA and VE in my calibrations, and the AVIA in question is Guy's original, classic test disc. But Guy mentioned AVIA Pro.

Guy, if you are still tuned in to this thread, could you give me some info on the differences, and whether I should buy the Pro version, if I already have AVIA? Thanks.

 

[Robert P. Jones]

Actually the Mits grayscale registers are global only on User Low, and on User High are local to the scanrate involved when in Service Mode. You will find the grayscale registers in SM for Low with an L at the end, and for High with an H at the end.

I don't know if the unit in question had the registers required for decoder realignment in it, but if it has a built-in HD tuner, chances are it does. They are R-YR, R-YB, G-YR, and G-YB, in the Video Chroma SM, xx57.

Mit has had red push designed into their colorations paradigm since long before ANYB0DY's HDreadys came about. In the older versions it was defeatable on certain model years in the User Color Bias section, under the heading of "Accurate". As opposed to Skin-tone and Average, both of which were red pushed. If I had had Guy's AVIA at that time, I woulda known that about my VS-6017, which had those User settings available.

Whenever there is red push - or any other kind, today I cal'd a Sony LCD 50" HDready and had to deal with red diminish! - you cannot trust the blue isolation/filter test. You will get blue perfect, and the red will still stick out like a sore thumb on a redpushed system.

The only way to do it without realignment of the color decoder or addition of an attenuator if you have your info going in on component inputs, is to do it very carefully by eye and hope for the best.

Mr Bob

PS - I have always used both AVIA and VE in my calibrations, and the AVIA in question is Guy's original, classic test disc. But Guy mentioned AVIA Pro.

Guy, if you are still tuned in to this thread, could you give me some info on the differences, and whether I should buy the Pro version, if I already have AVIA? Thanks.

 

[Guy Kuo]

Bob, I haven't described Avia PRO in much detail on this forum because it is very definitely a professional leve product, rather than an updated consumer disc. The Avia PRO package is a seven disc set with a tremendously expanded set of test options for the profesional calibrator, engineer, or equipment reviewer. It is reasonably priced for a professional who can recover the expense, but only a very select few home theater enthusiast will be able to obtain the $400 box set.

Avia Pro comes in a padded binder which holds extensive printed documentation about the test signals. Included are the SMPTE test disc which contains very difficult material to properly display. The CEA standards disc contains signals used in industry for verifying DVD audio and video performance at the factory. The RPG Room Optimizer and Room Sizer programs are on a CD-ROM. These allow modeling of room and speakers to optimize response. Two audio test discs for DVD-A and DVD-video audio (will ship later) provide extensive audio test signals. The discs which I directly created video test signals are the 16:9 and 4:3 Ovation Avia PRO test DVD's. These supply 1,000 video test patterns (3,000 to 5,000 if you count the variations separately).

The video test set includes many features which are not available in the consumer Avia. I paid great attention to providing tools for the calibrator. There are special suites of test patterns for CRT and fixed panel displays. The suites consolidate the most commonly used patterns for the category. Navigation is widely acclaimed by owners as being easier than even AVIA. The patterns stay on screen indefinitely. Gray scale calibration is speeded by sets of windows which let you select and use the hi/medium/low windows of interest. You can the very quickly navigate within each quadruplet of windows with a press of the next or prev button. Every window includes indicators of black level. High level windows include clipping markers.

I could go on and on, but literally there is too much describe. Some reviews are beginning to appear but they are on other forums so I cannot provide links. The patterns are much cleaner and accurate than ever before. The leap forward from Avia to Avia PRO is like going from a bicycle to a nice sports car.

To give you an idea of what Avia PRO is like, here are some excerpts from the manual...

Introduction

This chapter discusses the video test signals found on the Avia PRO Video Test DVD and its supplemental 4:3 Ratio DVD. Avia PRO contains the most extensive set of video setup and test signals ever released. Over 1,000 new digitally generated and mastered test signals (5,000 counting variants) are included. Professional calibrators, engineers, reviewers, and designers will recognize familiar signals in Avia PRO, but many patterns include extra test features or are completely new. We recommend reading this chapter to learn about the new video tests and features in Avia PRO.

Avia PRO’s extensive test set enables calibrators to choose a pattern tailored to the task. Examples include: geometry grids selectable in intensity, tinting, and spacing; grayscale windows available in 2.5, 5 and 10 IRE increments; and APL intensities adjustable during black level adjust-ment. These and other signal options allow Avia PRO users to enjoy a near custom fit between pattern and task.

Avia PRO Video Test DVD's were designed for professional users rather than consumers. They behave as a responsive test signal source rather than an instructional video with incidental calibration signals. Professional users demand immediate access to test signals with a minimum of material "in the way." Avia PRO Video Test DVD's feature quick access of all test patterns via logically arranged menus or chapter/title number navigation.

As a professional level suite, Avia PRO was freed of limitations that protect lay users but interfere with experts. For instance, automatic pattern advance is the default on the consumer Avia Guide to Home Theater DVD. This appropriately reduced screen burn-in risk for consumers, but calibrators, reviewers, and engineers benefit from explicit control of signal changes. Patterns in Avia PRO do not advance unless explicitly directed by the user.

Avia PRO on-disc signal arrangement took into consideration the tasks commonly performed by calibrators. Separate suites of patterns were culled for CRT and fixed panel (digital) display setup. Each suite features patterns selected to meet the special needs of that class display. The CRT suite places greater emphasis on geometry and convergence patterns while the fixed panel suite includes more scaling, gamma tracking, and signal limit tests.

Small sets of patterns were linked together to speed commonly performed tasks. For instance, navigating between window patterns during grayscale calibration was cumbersome before Avia PRO. Calibrators either had to accept the high and low IRE window patterns that happened to be adjacent on a disc or inconveniently step between their desired window patterns. Avia PRO users can choose the high and low IRE window sets appropriate for the situation. Once window values are selected, Avia PRO speeds navigation between the desired windows during grayscale calibration.

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Window Patterns

Grayscale calibration is an important and often performed task. Avia PRO provides new tools to make the process faster and easier. Window patterns in Avia PRO enable black level verification, white level clipping avoidance, and automated grayscale measurement. Windows are available in increments as fine as 2.5 IRE and range from below black to above white. Professional calibrators now gain the ability to select their high and low intensity windows rather than accept the values supplied on other discs or suffer cumbersome navigation between two value windows. Avia PRO includes windows in "sets" which provide easy selection and rapid navigation between desired IRE window levels.

Gray Windows: Animated black level bars, edge transition tests, and IRE level labels are integrated into each window pattern. (Black level falsely elevated for illustrative purposes)

Waveform of Window Pattern: Black level bars are at 4 IRE below black, 1 IRE above black, and 2 IRE above black.

Higher IRE level window patterns include Avia Pro's three white level bars to indicate clipping.

Waveform of High IRE Window Pattern: Windows at 90 IRE or higher include white level bars at 2 IRE below white, 1 IRE below white, and 1 IRE above white.

Previous calibration DVD’s supplied window patterns in much more limited configurations. Avia PRO supplies grayscale calibration windows in three manual sequences, three automated sequences, and user selectable quadruplet sets.

Manual Sequences: Windows are available in ascending order in 2.5 IRE, 5 IRE, or 10 IRE increments. The 2.5 IRE increment sequence starts below black and extends above white. Each window displays indefinitely until the "next chapter" button is pressed on the DVD remote. Remote control "return" or "previous chapter" buttons step backwards in the sequence. "Menu" returns to the grayscale sequence menu. Individual windows are selectable from the 5 and 10 IRE menus, but that would require too many menu items in the 2.5 IRE sequence. For the 2.5 IRE sequence, every other window is directly accessible. The window intensities between those in the menu can be accessed with a subsequent press of the "next chapter" button.

Note: The DVD specification limits the total number of items permitted on a DVD menu. This limit is higher for 4:3 aspect ratio menus than for 16:9 menus. For this reason, the disc intentionally uses 4:3 menus when a large number of choices are listed.

Automated Sequences: Grayscale calibration report generation can be tedious. Avia PRO includes automated sequences of grayscale windows for use with computer controlled measurement equipment. Each window of the sequence is displayed for 5 seconds before advancing to the next window. Just before each window appears, a synchronization tone triggers the sensing equipment to read a sample. Automated sequences are supplied in 2.5 IRE, 5 IRE, or 10 IRE increments.

Calibration Sets: The optimum high and low window values for calibration are not the same for every type of display and instrument. AVIA PRO makes it easy to select and use the appropriate intensities instead of accepting limited choices on disc or working through slow navigation. Calibration sets are quadruplets of four patterns that form self contained loops. Each quadruplet contains a high and a low window as well as a middle window and black level screen. The middle window is used to verify middle grayscale tracking as the ends are adjusted. The black level screen serves as an additional check of black level correctness. The window patterns themselves contain black level bars and steps to allow continual monitoring of black level during gray scale calibration.

Window quadruplets give professional calibrator easy and rapid navigation between desired high and low windows as well as black and middle patterns to check progress. Quadruplet combinations were designed to cover a wide range of conditions. They have the following combinations of IRE windows + black:

40 / 70 / 100 / black

40 / 65 / 90 / black

40 / 60 / 80 / black

30 / 65 / 100 / black

30 / 60 / 90 / black

30 / 55 / 80 / black

20 / 65 / 100 / black

20 / 60 / 90 / black

20 / 50 / 80 / black

Grayscale calibration is faster, more convenient, and flexible with Avia PRO.

Edge Transitions: Three types of horizontal edge transitions are present in each window pattern. These are useful for testing system response for ringing, bandwidth, and group delay. Transitions in the upper third of each window are instantaneous. Transitions in the middle third are T2-Steps with a critical frequency of 6.75 MHz (NTSC DVD limit). Transitions in the lower third are T2-Steps with a critical frequency of 4.0 MHz (NTSC broadcast limit).

The upper third, instantaneous transitions are very severe tests of system frequency response and timing. Very few display systems other than home theater PC's can reproduce transitions of the upper third without ringing. The middle third transitions are less severe and should be cleanly reproducible by higher performance home cinema systems with sharpness correctly set. The bottom third transitions are significantly frequency limited and should be cleanly reproducible on most video systems when sharpness is correctly set.

 

[Robert P. Jones]

Whoa!

You been busy!

My compliments to the chef. Now if we could only get all the TV channels in the country - HD and nonHD - to use these, the term NTSC would no longer mean Never The Same Color...

And every manufacturer... Yeah. I'm sure the manufacturers are not even using the regular AVIA...

Great work!

Mr Bob

PS - ISF says the AVIA grayscale patterns are not correct. Has this been remedied on the PRO version? I know it has on the Sound and Vision disc -

I also find the Montage of Images on VE quite helpful when color and tint calibration has to be done by eye, due to red push making the blue isolation test invalid and therefore screwing up the fleshtones. You can't fudge on the fleshtones...

Any montages of images on your discs?

Also, I heard that the ideal overscan on DVE is 2.5%. I know that for RPTVs, 4-4.5% on AVIA is best. Are the 2 measurements actually different? Haven't tried the DVE yet. The AVIA one has been doing excellently on my calibrations for years and I am not really motivated to use anything else.

 

[Guy Kuo]

The encoding problem was not only corrected for Avia PRO, but new, custom encoders by Innobits allowed far higher precision and detail in the patterns than ever before possible. Some people who have been examining the discs with oscilloscopes have been astounded by the signal quality.

For the calibrator, the biggest changes are the new convenience features and flexibility. You are very likely to find a pattern that fits the situation. Even convergence grids have variable size so you can use what you want instead of working with the few spacings normally available.

 

[Vader]

Thanks, all! I don't think I will be messing with these beyond what I can do in the user menu (until the budget will allow for a full ISF calibration). Until then, I will just get as close as I can using AVIA and DVE... The information all of you afforded me is great, albeit somewhat above my head... Thanks again!